On my MTB: This cage like thing covering the rear derailleur was loose and was making a lot of noise when I was riding. I removed it temporarily and it seems fine to do so. Am I correct?

What is the technical name of this component and why is it present?

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1 Answer 1


It's known as a derailleur guard. It is designed to protect your derailleur against side impacts that may damage it.

It's not a problem to remove it, i've never had one myself, nor do I know anyone that has had one and our derailleurs are all still fine.

It's probably a handy thing to have if you are parking your bike in large communal bike shelters where other users are perhaps not as careful as they could be.

  • it is one of those things that are hard to search for when you don't know the name. now that I know it is a derailleur guard, I see a lot of material. thanks!
    – deepakkt
    Jun 11, 2022 at 13:38
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    Additionally, it protects against side impacts from dropping the bike right-side down on the ground. Protection extends to the hanger as well as the mech.
    – Criggie
    Jun 12, 2022 at 19:23
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    It will protect your derailleur and its hanger but at the cost of endangering the frame. Jun 12, 2022 at 20:16
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    @VladimirFГероямслава are you sure? I think it would need to be a very fragile frame and a very solid guard.
    – pateksan
    Jun 12, 2022 at 22:09
  • My experience is they are build soft, more often than not, the protector bends and jams the derailleur, has to be removed and is never replaced. However, I have seen a couple of cases where removing a bent protector would have been a better outcome for the rider - car rack and bicycle stand, not riding inflicted damage.
    – mattnz
    Jun 13, 2022 at 23:31

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